Laser diodes have a vast field of applications and they are propelling the optical communications field. This is due to their small size, relatively simple construction and high reliability. In order to support higher functionality of such light sources, many configurations, in which an “on-chip” laser is composed of or attached to multiple functional segments, have been introduced in recent years. The following are some examples of the known light sources of the kind specified:                (1) C3 laser, where laser cavities are monolithically cascaded (U.S. Pat. No. 4,622,671);        (2) DBR laser, where the active segment(s) is(are) sandwiched between two gratings segments (Y. Suematsu, S. Arai and K. Kishino, “Dynamic Single Mode Semiconductor Laser with a Distributed Reflector”, IEEE J of Lightwave Tech. LT-1, 161 (1983));        (3) Master oscillator power amplifier (MOPA), where the laser segment is attached to a power amplifier segment (U.S. Pat. No. 5,126,876); and        (4) a monolithically integrated externally modulated laser, where the laser segment is attached to an external modulator segment (U.S. Pat. No. 5,548,607)        
All the above prior art configurations suffer from crucial difficulties in their manufacture and in the possibility of extending their functionality. One of the key problems is to generate an on-chip laser mirror, in which the functionally different segments of the laser are separated from each other. Various technologies have been suggested to implement this idea, such as on-chip etching or cleaving, or using sub-micrometer period gratings. However, due to the technological difficulties, all existing devices of the kind specified, such as tunable integrated sources, MOPA, monolithically mode locked lasers and monolithically externally modulated lasers, are difficult to fabricate and thus expensive.